var elem = '#test1'
var data = [
  {
    title: '江西', //一级菜单
    children: [
      {
        title: '南昌', //二级菜单
        children: [
          {
            title: '高新区', //三级菜单
            href: 'https://www.baidu.com',
            //…… //以此类推，可无限层级
          },
        ],
      },
    ],
  },
  {
    title: '陕西', //一级菜单
    children: [
      {
        title: '西安', //二级菜单
        href: 'https://www.baidu.com',
      },
    ],
  },
  {
    id: 111,
  },
]
